1. Field
The present disclosure relates to Global Navigation Satellite System (GNSS) devices and, more specifically, to performing localization using a GNSS device.
2. Related Art
Navigation receivers that use global navigation satellite systems, such as GPS or GLONASS (hereinafter collectively referred to as “GNSS”), enable a highly accurate determination of the position of the receiver. The satellite signals may comprise carrier signals that are modulated by pseudo-random binary codes and that, on the receiver side, may be used to measure the delay relative to a local reference clock. These delay measurements may be used to determine the pseudo-ranges between the receiver and the satellites. The pseudo-ranges are not true geometric ranges because the receiver's local clock may be different from the satellite onboard clocks. If the number of satellites in sight is greater than or equal to four, then the measured pseudo-ranges can be processed to determine the user's single point location as represented by a vector X=(x, y, z)T, as well as to compensate for the receiver clock offset.
In geodetic applications, many different coordinate systems may be used. For example, in GPS applications based on the WGS-84 coordinate system (which is a so called “Earth-Center Earth-Fixed” coordinate system), coordinates for locations may be defined using an X, Y, Z Cartesian axis centered about the center of the Earth. Other systems, such as the North American Datum 85 (NAD-85) coordinate system, may implement semi-localized Latitude-Longitude-Altitude coordinate systems. There are also “State Plane” coordinate systems that project portions of the Earth onto flat surfaces called “zones.” For example, each state in United States may be represented by one or more zones. In these systems, over 3,000 such flat Earth projections exist world-wide.
In many geodetic applications (e.g., stakeout), designers of roads, buildings, or the like, may generate their designs using computer-aided design (CAD) tools that identify locations of points using an arbitrary coordinate system (referred to herein as a “local system”). For example, the CAD tools may use a North-East-Up flat Earth coordinate system having an arbitrary center (e.g., 0, 0, 0). When the design is transferred from the computer to a real-world location, the locations within the arbitrary coordinate system of the CAD tool may be converted into corresponding locations within the geodetic system that will be used (e.g., WGS-84, NAD-85, a State Plane coordinate system, or the like) (referred to herein as an “actual system”). The process of converting locations within the local system to the actual system is often referred to as “localization.”
In some example localization processes, three or more locations within the local system may be surveyed to determine their corresponding locations within the actual system. Typically, users are required to manually generate the three or more local-actual pairs by selecting locations within the local system and their corresponding locations within the actual system from a list of locations. Using the generated local-actual pairs, a localization process can be used to covert locations within the local system into locations within the actual system.
While the manual process of selecting local-actual pairs can be used to effectively provide the input necessary for many localization processes, it can be a time-consuming and confusing process for the user. For instance, conventional software applications may require the user to specify the local locations, specify the actual locations, and then manually pair the local and actual locations.